Irish detectives have arrested two men in connection with the murder of one of MI5’s most important spies inside the IRA.

The pair have been detained for questioning about the murder of former leading Sinn Féin member Denis Donaldson in Co Donegal in 2006.

The Garda Síochána said the men, who are in their 40s and 70s, were detained on Tuesday under the Irish Republic’s Offences Against the State Act.

They are being held at Letterkenny garda station in Co Donegal. Donaldson, a former close associate of Sinn Féin’s president, Gerry Adams, was killed by a shotgun blast as he answered the door to his cottage near Glenties in April 2006.

The 55-year-old had been exposed months before his death as an MI5 agent working inside Sinn Féin and the IRA. Dissident republican terror group the Real IRA admitted responsibility for the murder.

Prior to his exposure as a British spy, Donaldson was a prominent figure in the republican movement and eventually became head of Sinn Féin’s administrative team in the Stormont parliament in Belfast.

The inquest into his death has been delayed at least 19 times, with his family taking legal action against the authorities in Ireland over the delays.

There have been allegations that a journal belonging to Donaldson was found in his cottage and, due to its sensitive contents, the Irish police have consistently applied for postponements of the inquest.

"Everyone, Republican or otherwise has their own particular part to play. No part is too great or too small, no one is too old or too young to do something."

~Bobby Sands 1954-1981~

'Mother Erin'

Two divine persons in one. A mother lamenting her children in bondage. A girl ravished by the Saxon, who weeps over her stringless harp. But her young champions keep watch in the mountains, awaiting the dawn of the bright sun of Freedom. They will gather around her with pikes and swords.